NMR of Mitochondrial Transporters in Cardiac Hypertrophy

描述（由申请人提供）：该提案利用了我们在先前资助期间的最新发现，即肥大心肌中转运蛋白介导的代谢途径的代偿激活，以对抗长链游离脂肪酸（LCFA）氧化率降低和丙酮酸脱氢酶（PDH）活性受限。我们已经发现，在压力过载、肥厚率高的心脏中，LCFA氧化和TCA循环通量率之间存在不匹配，这种不匹配不能通过PDH增加葡萄糖氧化来补偿。更确切地说，葡萄糖氧化的替代方法是通过增加的倒转通量进入TCA循环的第二段，正如胞质中间体加速交换机制以补充TCA循环一样。我们假设，在压力过载肥厚的代偿阶段，为TCA循环提供燃料的替代途径代表了支持氧化能量产生的适应性，但效率较低的机制。总体目标是通过药理学和基因组操作来干预大鼠心脏代偿期和后期失代偿性肥厚期间发生的代谢适应。我们的实验目的将是：1)通过在PDH中增加丙酮酸进入TCA循环的药理学方法，探索中间代谢中这种适应性变化的能量含义；2)阐明OMC活性增加（一种将胞质还原等价物转移到线粒体的蛋白质）与肥大心脏中糖酵解速率与葡萄糖氧化解耦导致的胞质氧化还原负荷减轻之间的联系；3)利用我们在心脏特异性体内基因转移效率方面的最新进展，阐明OMC在肥厚性心脏中通过诱导OMC过表达和OMC减少来提供TCA循环中间体的调节作用；4)结合13C NMR和心脏MRI显微镜，通过探索肥厚心脏和扩张心脏的潜在区别，研究代谢适应和壁应变之间的联系。新的实验探索了特定小鼠模型之间的代谢差异：同心圆肥大（蛋白激酶C β过表达）与扩张型心肌病（PKC epsilon过表达），我们预计将在左心室壁显示不同的应变谱。这项研究将确定降低能量生产效率的适应性机制，并可能有助于心力衰竭的进展。

DESCRIPTION (provided by applicant): This proposal exploits our recent findings, during the previously funded period, of compensatory activation of transporter mediated metabolic pathways in the hypertrophied myocardium that counter reduced rates of long chain free fatty acid (LCFA) oxidation and limited pyruvate dehydrogenase (PDH) activity. We have identified a mismatch between LCFA oxidation and TCA cycle flux rates in the pressure overloaded, hypertrophic rate heart that is not compensated by increased glucose oxidation via PDH. Rather, alternative means of glucose oxidation via increased anaplerotic flux into the second span of the TCA cycle are in evidence, as are accelerated exchange mechanisms for cytosolic intermediates to supplement the TCA cycle. We hypothesize that recruitment of alternative pathways to fuel the TCA cycle in the compensatory phase of pressure overload hypertrophy represent adaptive, yet less efficient mechanisms for supporting oxidative energy production. The overall goal is to intervene via pharmacologic and genomic manipulation of the metabolic adaptations that occur during compensated and later stage, decompensated hypertrophy in rat hearts. Our experimental aims will 1) explore the energetic implications of such adaptive changes in intermediary metabolism by pharmacologically augmenting pyruvate entry into the TCA cycle at PDH; 2) elucidate the link between increased OMC activity, a protein transferring cytosolic reducing equivalents into the mitochondria, and alleviation of the cytosolic redox load due to uncoupling of glycolytic rate from glucose oxidation in the hypertrophic heart; 3) exploit our newly developed advances in the efficiency of cardiac-specific in vivo gene transfer to elucidate the regulatory role of OMC in providing TCA cycle intermediates via induced OMC overexpression and OMC reductions in hypertrophic hearts; 4) combine 13C NMR and cardiac MRI microscopy to investigate the link between metabolic adaptations and wall strain by exploring potential distinctions between hypertrophic and dilated hearts. Novel experiments explore the metabolic distinctions between specific murine mouse models of concentric hypertrophy (protein kinase C beta overexpression) versus dilated cardiomyopathy (PKC epsilon overexpression) which we anticipate will display distinct strain profiles across the left ventricular wall. The research will define adaptive mechanisms that reduce energy production efficiency and may contribute to the progression toward heart failure.